1. Field of the Invention
The invention relates to composite compositions having matrices of polymer networks and dispersed phases of particulate and/or fibrous materials, which have excellent mechanical properties, rendering them suitable for use in load bearing applications, such as in building materials. The composites are stable to weathering, can be molded and colored to desired functional and aesthetic characteristics, and are environmentally friendly, since they can make use of recycled particulate or fibrous materials as the dispersed phase.
2. Description of Related Art
Polymeric composite materials that contain organic or inorganic filler materials have become desirable for a variety of uses because of their excellent mechanical properties, weathering stability, and environmental friendliness.
These materials can be are relatively low density, due to their foaming, or high density when unfoamed, but are extremely strong, due to the reinforcing particles or fibers used throughout. Their polymer content also gives them good toughness (i.e., resistance to brittle fracture), and good resistance to degradation from weathering when they are exposed to the environment. This combination of properties renders some polymeric composite materials very desirable for use in building materials, such as roofing materials, decorative or architectural products, outdoor products, insulation panels, and the like.
In addition, the filler materials used need not be virgin materials, and can desirably be recycled fibers or particulates formed as waste or by-product from industrial processes. Polymeric composites allow these materials to be advantageously reused, rather than present disposal problems.
Filled composite polymeric materials have been described in U.S. Pat. Nos. 5,302,634; 5,369,147; 5,548,315; and 5,604,260, the contents of each of which is incorporated herein by reference. However, the materials disclosed in these patents all use polyester polyurethane resins that are formed as the reaction products of unsaturated polyester polyols, saturated polyols, poly- or di-isocyanates, and a reactive monomer, such as styrene. The number of different reactants, and the complexity of the resulting process chemistry, adds increased cost to the preparation of these materials, both through added costs for materials inputs and through added capital costs for additional process equipment.
A filled closed cell foam material is disclosed in U.S. Pat. No. 4,661,533 (Stobby), but provides much lower densities than are desirable for structural building products. Moreover, Stobby does not disclose or suggest a composite material that is “self-skinning,” i.e., that forms a continuous skin on the surface of the material that covers and protects the material underneath, which is porous, and subject to visible scratching.